1. Field of the Invention
This invention relates to human venous insufficiency syndrome and the treatment thereof.
2. Description of the Prior Art
By way of background, venous insufficiency syndrome (VIS) is a chronic medical condition in which the ability of the venous system to maintain venous blood return to the heart and adequate venous pressure in the patient""s extremities is impaired. Functional incompetency of the vein valves, due to venous valve prolapse (xe2x80x9cfloppy valve syndromexe2x80x9d) and other conditions, is a common cause of this disorder.
Current methods of treating valvular incompetency include implantation of prosthetic vein valves. U.S. Pat. No. 4,851,001, issued to Applicant on Jul. 25, 1989, discloses such a prosthesis.
Recent re-evaluation of Applicant""s patented prosthetic vein valve suggests that improvements can be made in the areas of valve functionality, valve securement, and blood clotting response. Applicant has identified a need for a new and improved prosthetic vein valve.
The foregoing problems are solved by an improved prosthetic valve adapted to be inserted into a blood vessel and held in a desired position therein. The valve includes an annular support ring having a longitudinal axis and defining a substantially circular central opening for passage of blood. The support ring has an outer wall that may be formed with a central annular depression. A leaflet is mounted on the support ring for pivotal movement between a closed position wherein the leaflet substantially blocks the central opening and an open position wherein blood is permitted through the opening. The valve is adapted to be inserted into the blood vessel such that the support ring longitudinal axis is substantially coincident with an axis of elongation of said blood vessel and held in such position in suitable fashion, such as by suturing or by way of a tightened cord holding a proximate portion of the blood vessel in the annular depression.
The valve may additionally include a radial passage extending through the support ring and a stem extending radially outwardly from the radial passage. The stem has a central bore communicating with the radial passage and is adapted to extend through the wall of the blood vessel when the valve is mounted therein and provide an entry for introduction of anti-clotting agents and other materials proximate the valve. The valve may further include a plurality of external stabilizer elements adapted to extend through the wall of the blood vessel and provide locations for attaching a valve stabilizing assembly. The stabilizing assembly may include a plurality of stabilizing arms that extend outwardly to engage body tissue surrounding the vein, or inwardly to engage the vein at a location which is spaced from the support ring. In the latter configuration, the stabilizing assembly may further include a stabilizing ring that extends around the vein at the spaced location.
The support ring can also be made to be deformable or thermally expandable to facilitate insertion and securement thereof in the vein. In a deformable configuration the support ring can be folded or radially compressed prior to insertion in the vein and then released when the valve is correctly positioned. In the thermally expandable configuration, the support ring can be thermally cooled prior to insertion in the vein and then allowed to expand when the valve is properly positioned.
The prosthetic valve of the invention can be implanted according to a novel method that includes providing a prosthetic valve as summarized above, forming an opening in the blood vessel at a location therein that is spaced from a location at which the valve is desired to be implanted, inserting the valve through the formed opening to such desired location at which the valve is to be implanted and orienting the valve so that the support ring longitudinal axis is substantially coincident with an axis of elongation of the blood vessel. The valve can be sutured. Or, a cord can be tightened about the outer wall of the blood vessel such that the proximate portion of the blood vessel is caused to assume the contour of the annular depression. The cord is then tied in the tightened condition to secure the support ring in a desired position.